Hydrocarbon wax



1933- M. HENDERSON E1 AL 1,9375518 HYDROCARBON WAX Filed April 2a. 1931Jmmtom; 1 flnderson,

Lawrence a W W mr a 2 7 1 I Patented Dec. 5, 1933 UNITED STATES PATENTOFFICE HYDROCARBON WAX Application April 28, 1931. Serial No. 533,486

19 Claims.

The present invention concerns new wax products, particularlyhydrocarbon waxes which possess characteristic and novel properties. Aspeclfic aspect of our invention concerns waxes from crude petroleumsources. It also relates to a method for producing such new products. Itis to be understood that our invention is not to be limited because ofthe particular method for preparing our wax products herein disclosed,nor by reason of the particular specific sources thereof herein given.

Briefly, our new hydrocarbon waxes are more ductile, more workable, andmore sticky or tacky than hydrocarbon waxes heretofore known. They arefurther characterized in that they have higher refractive indices thanhydrocarbon waxes of corresponding melting points heretofore known,which latter may, in general, be characterized as hard, non-sticky, andrather brittle substances.

In many of the uses to which hydrocarbon waxes have been put in thepast, a great need has been felt for waxes having many of thecharacteristic hydrocarbon wax properties, but difiering from theordinary hydrocarbon waxes in other properties, such as plasticity,workability and stickiness. For example, if certain articles, such asthe well known waxed paper or waxed containers are impregnated or coatedwith the usual hydrocarbon waxes, as for example, for waterproofing oracid proofing, it is well known that the waxes will crack when sucharticles are subjected to use and ordinary handling at low temperatures,because the wax lacks ductility. In order to have a wax of desiredplastic and/or sticky properties, it has been necessary heretofore toemploy, either alone or admixed with hydrocarbon waxes, other materialssuch as beeswax, japan wax, and/or resins.

To provide waxes composed entirely of hydrocarbons, that are plastic,sticky and workable is among the objects of our invention. However, itis to be understood that our new products, because of their differentand distinctive properties, may be put to a multiplicity of uses inaddition to those given herein by way of illustration.

A brief account of ordinary hydrocarbon waxes and the usual processes bywhich they are manufactured will be of assistance in distinguishing suchwaxes from our novel wax products. Most crude petroleums, andparticularly those of the so-called parafiin-base or mixed-base types,contain certain hydrocarbons commonly known as paraflin wax. Such waxhas been found to contain at least three fundamentally distinctcrystalline types of wax, namely: plate, malcrystailine and needlewaxes. Present refining methods, particularly sweating, have a tendencyto remove the malcrystalline and needle type waxes with the oil, andleave as solid the plate type waxes, so that the finished waxes tend forthe most part to approach toward the plate type. In the usual methods ofrefining crude petroleum, the crude is subjected to distillation therebyto separate it into a number of fractions of varying volatilities andviscosities. The fraction known as parafiln distillate, which, ingeneral, is a fraction having a boiling range of the order of from about170 C. (340 F.) to about 310" 0. (590 F.), when distilled under anabsolute pressure of 10 mm. of mercury, and which ordinarily is obtainedfrom parafiin base and mixed base crudes, is separated into a solid waxfraction and a liquid oil fraction by chilling and filter-pressing. Thesolid fraction or crude wax collected in the filter press is known as"slack wax, and contains a large quantity of oil. This oil is removed orreduced by subjecting the slack wax to a "sweating" operation whichconsists essentially in fractionally melting and draining the oil and/orlower melting waxes from higher melting waxes. The waxes resulting fromthe sweating operation are then further refined by any of the well-knownprocesses, such as by treatment with sulphuric acid and/or percolationthrough fullers earth, The products so obtained are the ordinaryparaflin waxes of commerce, and are graded according to their meltingpoints, into products differing in hardness and other properties. All ofthese products however, may, in general, be classed as hard and brittle,except at temperatures approaching their melting points; furthermore.they tend to crystallize rather coarsely.

After the parafiin distillate cut, usually there is separated from thecrude during the distillation another higher boiling cut, known as thehigh viscosity fraction. This fraction also contains wax, but because ofits particular crystalline form, it does not lend itself to separationdirectly by filter-pressing. Instead, this fraction is usually coldsettled or centrifuged to eiTect a comparatively rough separation of thewax from the oil. The wax together with considerable oil, as it isseparated by the cold settling or centrifuging oporation, is known as"petrolatum stock, and contains a micro-crystalline form of waxgenerally known as slop wax. Certain high melting waxes are occasionallyobtained from petrolatum stock by repeated recrystallizations andsettlings from naphtha solution, which high melting waxes do not haverefractive indices of the order of those of our novel waxes ofcorresponding melting points. However, petrolatum stock cannot besuccessfully processed by either pressing or sweating. As a rule, thewax in petrolatum stock is not recovered, but is cracked or otherwisedisposed of.

There are, in addition to the wax sources aforesaid, the residual stockswhich contain a microcrystalline wax, commonly known as petrolatum wax.This wax usually is not processed into a finished wax product, butbecomes a slop wax, or in some cases, after separation is employed inthe production of petroleum jellies or the like.

From the aforesaid, it will be noted that, in general, there are threeclassifications of hydrocarbon waxes used among petroleum refiners,namely: 1. Parafiin wax, 2, slop wax, and 3, petrolatum wax. Thisclassification is not to be confused with the other classificationherein employed, which specifies: 1. Needle wax, 2, malcrystalline wax,and 3, plate wax. This latter classification has particular reference tocrystalline structure, while the former is a rough classification usedin refining practice and signifies in a measure the use to be made ofthe wax contained in a certain batch of material, and the method to beemployed in handling it.

In the further treatment of slack wax from the filter press, as referredto above in connection with the processing of paraffin distillates", thewax cake is melted and run into sweating pans, wherein it is cooled to atemperature substantially below its melting point, and thereafter heatedto cause the oil occluded in the slack wax to exude therefrom. The waxwhich is left after the first sweating is known as crude scale wax, andis usually resweated one or more times in the production of refinedwaxes. The oil which exudes from this crude scale wax on resweating,carries with it some waxes which roughly may be designated as waxintermediates". These waxes are to a large extent lost from the finalsweated wax products. Also, the oil passing from the wax in the firstsweating, generally referred to as "foots oil, carries with itsubstantial-quantities of waxes which are in general not recovered.

It will be seen, therefore, that the usual methods of wax recovery donot provide for the recovery of many waxes which may be of moderatelyhighmelting point,but which because of their high solubility in the oilare sweated out with and retained in the oil.

We have discovered that waxes which by prior processes remain in theoil, as pointed out above, may be recovered and upon recovery havehighly desirable properties. Further, we have succeeded in preparing aseries of hydrocarbon waxes of very desirable properties quite differentfrom those of the hydrocarbon waxes heretofore known. These waxes may beprepared from "foots oil, or intermediate waxes from the sweatingoperation, or from petrolatum stock or "slop wax", or in short, frompractically any oil which contains waxes lost by customary methods ofwax recovery, of which methods those given above are typical.

We may employ any of a variety of methods, as well as any of a varietyof starting materials. However, for a better understanding of ourinvention, we describe a specific process without intending to belimited thereto. 'Such description covers one satisfactory method 01'preparation of our novel wax products and a satisfactory choice ofstarting materials. Seventy-five parts of slack wax from a Mid-Continentcrude were mixed with twenty-five parts of petrolatum stock" from asimilar crude. This oil-wax mixture was de-oiled by dissolving it attemperatures of the order of 50 C. in ethylene dichloride, usingapproximately ninety parts of ethylene dichloride to ten parts of themixture. The solution was then cooled to between -15 C. and l0 C., andthe portion which crystallized out was again treated in the same way.This process was repeated until four recrystallizations had beeneffected. The resulting material from the last of the fourrecrystallizations, which was a sub-' stantially oil-free wax wasfractionally distilled, under an absolute pressure of approximately 10mm. of mercury using steam until 20% bottoms remained. The fractionswere collected, the first fraction containing 5% of the total volume ofthe material subjected to distillation. Then five 15% fractions, each ofa successively higher boiling range than the one preceding, werecollected. Each of the 15% fractions was split by means of fractionalcrystallization from ethylene dichloride in the manner in whichcrystallization was previously effected, except that the temperature wasso controlled that the desired quantity of wax was crystallized out ofeach fraction, using 9 parts by volume of ethylene dichloride to 1 partby volume of the fraction. The results of this procedure are shown inTable 1 given below:

Table 1 Crystallization "actions 7 DH. 5 Flow @W M.P. Wax M.P. c.

"o. No. 0. 33 2%?- 0-5 35.5 1 5-20 42 10 2 42.4 1.4210 51 10.5 4s 2l 340.0 1.4209 33.5 H 30 20-35 45 02 4 50.0 1.4253 40.5 as 00 3s 5 45.01.4245 :44. 11 0 3550 5a 35 0 55.4 1. 4282 45 a5 02 2s 1 55.5 1.4215 4554.5 01 as s 41.5 1.4252 25 12 0 50-55 51 so 0 54.0 1.4315 55.5 54 as 5410 01.0 1.4515 45.5 54 89 55 11 45.5 1.4551 24 1.5 0 55-50 52 as 12 10.01.4551 55 a1 a5 21 13 55.2 1.4395 40 -5 21 a5 14 45.0 1.4428 25 -10.5 020% 66.8 25 15 15.0 1.4484 50 30.5 55 Bottoms 29 15 54.0 1.4535 38.5 1024 24 11 50.3 1.4545 29.5 5 0 2; 18 320 1.4510 15 1 0 For example, the520% fraction was dissolved in ethylene dichloride and chilled until 19%thereof separated out. This 79% made up wax #2. The remaining 21% wasobtained by chilling the solution much further, as for example, to -15C., and was labeled wax #3. A similar mode of procedure was followed inobtaining the other waxes shown. The waxes were next given a treatmentfor color improvement, and their properties then determined. Waxes 2, 3,4, 6, '1, 9, 10 and 12 shown in Table 1 were each treated for colorimprovement with 18 pounds of fuming sulphuric acid per 100 pounds ofwax, at 15 to 25 C. The acidity was neutralized with sodium carbonateand the wax was then filtered through clay. Waxes 5, 8, and 13, shown inTable l, were treated similarly to the above mentioned waxes with theaddition of a further wash with 66 36. sulphuric acid before the sodiumcarbonate treatment. with waxes 11, 14, 15, 16, 17 and 18, shown in thetable, the treatment was confined to clay filtration.

Table 1 further indicates the properties of the waxes produced by thischoice of starting materials and treatment. In the table the meltingpoint was obtained by A. 8. T. M. method 13-87- 22. The refractive indexinn") was determined by a suitable refractometer at 80 C. Columns 7, 8and 9 designated respectively as, flow point C., 85 D. K. C., and D. H.at 30 0., show the hardness characteristics of the wax and were obtainedby means of an instrument known as the Durometer, supplied by the ShoreInstrument Manufacturing Company. This instrument consists of a plungerwhich is pressed against the wax and the depth of penetration of whichis indicated by readings on a dial ranging from 0 to 100. The 100Durometer reading indicates no penetration while the 0 reading indicatescomplete penetration. The dew point (column 'i) is the lowesttemperature at which a 0 hardness reading is obtained. The 85 D. H.reading is the temperature at which the Durometer records 85 hardness,and the D. H. at 30 C. reading is the actual Durometer scale reading at30 C. It will be seen that all three points are measures of the hardnesscharacteristics and their variation with temperature. The products shownin Table l are capable of some variation by varying the treatment, butit is not hoped that all the waxes which we hereinafter claim as novelcan be advantageously produced with this single combination of startingmaterials. As another choice of starting materials, we may choose amixture of oil and wax intermediates which result from a normal sweatingoperation, and treat it similarly to the above described process, or wemay modify the process in various ways which will become apparent to oneskilled in the art, from what has been set forth above. Again, we mayemploy a combination of fonts oil, slack wax, and slop wax as thestarting material. Or again, for a special purpose, we may extract thewax which is dissolved in the oil passing out of the filter press, andeither alone or in combination with wax intermediates, petrolatum stock,foots oil and/ or normal finished wax products, treat the combination,for example, by the process indicated above or a modification thereof,and thereby finish with a set of products differing from those derivedfrom other combinations of starting materials or modes of processing.

By processing a number of combinations of starting materials, either bythe process outlined above, or by a modification thereof, a series ofwaxes may be produced which for a given melting point have varyingrefractive indices. Also, we have prepared waxes whose boiling points,hardness, ductility, and stickiness vary, as does the refractive index,for a given melting point. In general, the wax of highest refractiveindex will be softest, stickiest, and most ductile. We have been able toprepare a series of waxes of the same general degree of hardness,ductility or stickiness, but with a wide range of melting points; or, inother words, we have been able to prepare waxes of the same meltingpoints, but with a wide range of hardness, ductility, stickiness, andboiling points.

These novel waxes may be roughly differentiated from the normalhydrocarbon waxes of corresponding melting points in one ormore of thefollowing respects:

1. They possess much higher boiling points than the corresponding waxesheretofore known;

2. They are much softer and more sticky than the corresponding waxesheretofore known;

3. Their crystalline structure is much finer than the correspondingwaxes previously known;

4. Their indices of refraction are substantially higher than thecorresponding known waxes;

5. Their molecular weights are much higher than the corresponding lmownwaxes.

While all of these differences are significant. we regard the relationbetween melting point and refractive index asthe best single criterionto differentiate our hydrocarbon waxes from those known heretofore, notbecause the refractive index is the most important point of distinction,but because no thoroughly satisfactory and universally accepted methodhas been developed for expressing the stickiness, ductility, or hardnessof waxy materials. However, it can be seen from the data in Table 1 thatthe refractive index serves as a fairly good criterion of those otherimportant properties.

The drawing is a graph which illustrates the differences between ourwaxes and the common parafiin waxes, on the basis of the meltingpointrefractive index relationship. Refractive indices at 80 C. areshown as the abscissa, and the melting points as determined by A. S. T.M. method No. D87--22 are shown as ordinates. On the graph the commontypes of paraffin waxes lie within a relatively narrow band havingrefractive indices as a rule falling numerically above and graphicallyto the right of that defined by the expression n=l.4000+0.00044 T, buthaving refractive indices falling numerically below or graphically tothe left of that defined by the expression n=l.40'70+0.00044 T, where nis refractive index at 80 C., and T is melting point in C. A few waxeshave been reported which fall outside of this band, but all,nevertheless, have refractive indices numerically below that defined bythe expression, n=1.4000+0.000'75 T. The waxes which we have made andwhich we claim as new, on the other hand, all have indices of refractiongreater than those derived from this last expression.

Herein and in the appended claims wherever "refractive index" isreferred to, we mean refractive index for the D line at 80 C.

We have found that the further our waxes lie from the normal paraffinwaxes on a graph as shown in the drawing, or the greater amount by whichtheir refractive indices exceed the values computed from the expression,rt -11.40004- 0.00075 T, the more distinctive their properties becomefrom those of the previously known waxes. This is noticed particularlyin an increased pliability and decreased brittleness of the wax even attemperatures far below their melting points. For example, we find thatwaxes whose refractive indices are numerically greater than the valuederived from the expression n=l.4050+0.00075 T have more pronouncedproperties than those less than this value, and that those waxes whoserefractive indices exceed the figure given by the expressionn=l.4l+0,00075 T are even more unusual. Our most unusual waxes haverefractive indices greater than l.4250+0.000 T.

As an example of the differences in hardness characteristics between ournovel waxes and those heretofore known, one of our novel waxes with amelting point of 54 C. has a durometer hardness of less than attemperatures above 10 C. That is, this wax retains an appreciable degreeof softness at a temperature 44 C. below its melting point. This novelwax has a refractive index greater than that given by the formulan=l.4050+0.000'75 T. A normal hydrocarbon wax product of correspondingmelting point. 54.3 0., typical of those heretofore known, reachesdurometer hardness at 215 C., which is only 26.8 0., below its meltingpoint. As a second example of such diiference, one of our novel waxeswith a melting point of 43.6" C. reaches 85 durometer hardness at atemperature 50.6 C. below its melting point, whereas a typical normalhydrocarbon wax product of the known type, having a melting point of 45C., attains a corresponding hardness only 33.5 C. below its meltingpoint. This second novel wax has a refractive index greater than thatgiven by the formula n=1.4000+0.000'l5 T.

While by suitable choice of the starting materials and process ofpreparation, we have been able to extend the melting points of our novelwaxes at will both up and down, we have been most interested in thoseproducts with melting points between 25 C. and 75 C. Those products withmelting points below 50 (3., are in general useful where waxes withmelting points similar to those of the normal paraflln iwaxes aredesired, but where greater flexibility and less brittleness arerequired. As typical of some of the novel waxes which we have preparedwe have shown in Table 2 below the melting points and refractive indicesof a number of these:

Table 2 M.P 11p" We have shown in Table 2, by way of illustration of ournovel waxes, waxes ranging in refractive index up to substantially1.4800, and while waxes above this point are not shown, we are able bysuitable treatment as described, or modifications which will be obviousfrom what has been said heretofore, to prepare waxes not confined to therange illustrated.

Oil wax mixtures may possibly be obtained, which have relatively highindices of refraction. However, our novel products are distinct fromthese in that they are substantially oil-free waxes. This is shown bythe fact that they may be substantially completely (98% or more)recrystallized from ethylene dichloride at 0 F., using nine volumes ofethylene dichloride per volume of wax, and furthermore, that theproperties, for example the refractive index-melting point relationshipof such recrystallized waxes, will be substantially the same as those ofthe original materials.

A discumion of the various and sundry uses to which our new wax productscan be put, other than what has been stated briefly heretofore, wouldrequire more elaboration than need here be given. It suillces to directattention to the fact that our invention has made it possible to producesubstantially oil-free hydrocarbon waxes of a very wide range, ofproperties, such as have not been known heretofore.

While herein we have given crude petroleum, by way of example, as aspecific source from which our. novel products may be prepared, we donot intend to limit ourselves thereby, but insofar as products areconcerned intend to include all hydrocarbon waxes which come within thescope of the appended claims, whether they be derived from petroleum,oil shale, 'oaokerite, asphalt, or other similar crude materials, orfrom products resulting from the carbonization of coal, or even fromproducts derived synthetically.

It is to be understood that, while ethylene dichloride is specified as adesirable solvent to be employed in the process of producing our novelwaxes various other equivalent organic and/or inorganic solvents mayserve as substitutes therefor, any suitable solvent being withinourcontemplation.

The steps involving color removal herein speciflcally set forth, may bevaried or even omitted without the resulting product being beyond thescope of our invention. Also where steam is specified as the distillingaid in the fractional distillation of the oil-free wax, it is to beunderstood that other non-reacting distilling aids may be used assubstitutes therefor.

In the appended claims, when melting points are referred to, we meanmelting points measured by A. S. T M. method D-87-22.

What we claim is: V

1. A substantially oil-free hydrocarbon wax having a refractive indexmeasured at 80 C. greater than that derived from the expressionn=l.4000+0.000'75 T, where n denotes the value of the refractive indexand 7 denotes the melting point of the wax in C.

2. A substantially oil-free hydrocarbon wax having a refractive indexmeasured at 80 C. 1 5 greater than that derived from the expressionn=l.4050+0.000'l5 T, where n denotes the value of the refractive indexand T denotes the melting point of the wax in C.

3. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 75 C., and having a refractive index measured at 80 C.greater than that derived from the expression n=1.4000+0.00075 T, wheren denotes the value of the refractive index, and T denotes the meltingpoint of the wax in C.

4. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 75 C., and having a refractive index measured at 80 C.greater than that derived from the expression n=1.4050+0.00075 T, wheren denotes the value of the refractive index, and T denotes the meltingpoint of the wax in C.

5. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 75 0., and having a refractive index measured at 80 C.greater than that derived from the expression n=l.4150+0.00075 T, wheren denotes the value of the refractive index, and T denotes the meltingpoint of the wax in C.

6. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 15 C., and having a refractive index measured at 80 C.greater than that derived from the expression n=l.4250+0.00075 T, wheren denotes the value of the refractive index, and T denotes the meltingpoint of the wax in C.

'7. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 75 C..

and having a refractive index measured at 80 C.

greater than that derived from the expression n=1.4000+0.00075 T. andless than 1.4800, where n denotes the value of the refractive index, andT denotes the melting point of the wax in C.

8. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 50 C., and having a refractive index measured at 80 C.greater than that derived from the expression n=1.4000+0.00075 T, wheren denotes the value of the refractive index, and T denotes the meltingpoint of the wax in C.

9. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 50 C., and having a refractive index measured at 80 C.greater than that derived from the expression n=1.4000+0.00075 T, andless than 1.4800, where n denotes the values of the refractive index,and

-T denotes the melting point of the wax in C.

10. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 50 C., and having a refractive index measured at 80 C.greater than that derived from the expression n=1.4000+0.00075 T, andless than that derived from the expression n=1.4150+0.00075 T, where ndenotes the value of the refractive index, and T denotes the meltingpoint of the wax in C.

11. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 50 C.,

I and having a refractive index measured at 80 C.

greater than that derived from the expression n=1.4150+0.00075 T, andless than that derived from the expression, n=1.4250+0.00075 T, where ndenotes the value of the refractive index, and T denotes the meltingpoint of the wax in C.

12. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 50 C. and having a refractive index measured at 80 C.greater than that derived from the expression n=1.4250+0.00075 T, andless than 1.4800, where n denotes the valve of the refractive index, andT denotes the melting point of the wax in C.

13. A substantially oil-free hydrocarbon wax having a melting pointbetween 25 C. and 50 C., and having a refractive index measured at 80 C.greater than that derived from the expression n=1.4050+0.00075 T, andless than that derived from the expression n=1.4150+0.00075 T, where ndenotes the value of the refractive index. and T denotes the meltingpoint of the wax in C.

14. A substantially oil-free hydrocarbon wax having a melting pointbetween 50 C. and C.,

greater than that derived from the expression n=1.4000+0.00075 T, andless than 1.4800, where n denotes the value of the refractive index andT denotes the melting point of the wax in C.

16. A substantially oil-free hydrocarbon wax having a melting pointbetween 50 C. and 75 C., and having a refractive index measured at C.greater than that derived from the expression n=1.4000+0.00075 T, andless than that derived from the expression n=1.4150+0.00075 T, where ndenotes the value of the refractive index, and T denotes the meltingpoint of the wax in C.

17. A substantially oil-free hydrocarbon wax having a melting pointbetween 50 C. and 75 C., and having a refractive index measured at 80 C.greater than that derived from the expression n=1.4150+0.00075 T, andless than that derived from the expression n=1.4250+0.00075 T, where ndenotes the value of the refractive index, and T denotes the meltingpoint of the wax in C.

18. A substantially oil-free hydrocarbon wax having a melting pointbetween 50 C. and 75 C., and having a refractive index measured at 80 C.greater than that derived from the expression n=1.4250+0.00075 T, andless than 1.4800, where n denotes the value of the refractive index. andT denotes the melting point of the wax in C.

19. A substantially oil-free hydrocarbon wax having a melting pointbetween 50 C. and 75 C. and having a refractive index measured at 80 C.greater than that derived from the expression n=1.4050+0.00075 T, andless than that derived from the expression n=1.4150+0.00075 T, where ndenotes the value of the refractive index, and T denotes the meltingpoint of the wax in C.

LAWRENCE M. HENDERSON. SEYMOUR W. FERRIS. HENRY C. COWLES. JR.

